Convert a Parallels VM to Virtualbox

29 12 2009

In the last years I had the luck that my former employer paid for my license of Parallels Desktop, but this version is kind of outdated and since I only use virtualization for my year-end tax return statement I don’t see the point in spending money for a high-end virtualization solution.

As you may know, Sun offers an open source alternative to the big virtualization players called Virtualbox. Virtualbox is available on many different platforms and supports almost everything one might need from a plain and simple virtualization solution. Undoubted, when you have one software with a virtual machine up and running it is really hard to switch your vendor since everything is packed in vendor specific files with different hard disk images that are not compatible.

The first step is to install a current version of Virtualbox that you get directly from their website. Follow the installer to get it up and running until the point where you might want to create your new virtual machine.

The next step is to convert / copy the hard disks you used in your VM. When looking at the structure of a virtual machine the hard disk is basically everything you need. The rest is more or less configuration that can easily be moved to the new host system.

Luckily Virtualbox can directly mount Parallels or VMWare disk images, but there are a few pitfalls to avoid on the road to a working virtual machine.

  • What is my disk image file? – The easy answer is: the largest one, on Mac OS X don’t be confused with fact that the hdd file from Parallels is actually only a folder (right-click, show package contents) where the actual hard disk image is stored – now it’s the one with the .hds ending
  • Why can’t I open the file in Virtualbox? – You might get strange error messages regarding the type of the file, the answer to this question is twofold: first make sure the file is not a sparse disk image from Parallels and second, if this does not work out, rename the .hds file to .hdd
  • How do I convert my Parallels disk image from sparse to plain? – To perform this task, open the Parallels Image Tool and select the hard disk image you want to modify, now click on modify hard disk and select “convert to plain image” from the next page of the wizard. Depending on the size of you image, this can take quite a long time.

When the above steps succeeded you have almost everything in place to start the new virtual machine. Depending on your previous settings in Parallels configure the new image in Virtualbox. When you try to convert a Windows image from Parallels to Virtualbox there are a few other obstacles.

Usually Windows recognizes new hardware without any major problems and loads the device drives at system startup, but there is a case when Windows gets really picky about its environment: This is when you change the type of the IDE controller for example. If this is the case Windows will fail with a blue screen of death with error message 0x0000007B (no accessible boot device). The way to go is to repair the installation by using a Windows installation CD/DVD and start the repair mode. The repair mode for Windows XP e.g. is started by booting from the CD, select installation and when the list of available partitions is displayed choose “repair” from the menu list. Even though it might look like Windows is performing a fresh and clean installation of the system, it is actually preserving all settings and installed applications. But as always, it is better to have a backup.

As soon as the repair is finished you can directly boot into your new instance of a Virtualbox VM.

If you have any questions, feel free to ask.